AB0605 GIANT CELL ARTERITIS. PREVALENCE OF EXTRACRANIAL LARGE VESSEL VASCULITIS DIAGNOSED WITH 18-FDG POSITRON EMISSION TOMOGRAPHY.
Authors: V. Aldasoro, M. J. Garcia Velloso, J. Á. Richter Echevarria
Journal: Annals of the Rheumatic Diseases (2022)

Background The prevalence of extracranial involvement in giant cell arteritis (GCA) is unknown although there are series that has published prevalences of 20-65% depending on the technique used (1). Objectives To asses the prevalence of extracranial large vessel vasculitis (LVV) in GCA diagnosed by positron emisión tomography (PET) and to describe clinical and radiological features. Methods Prospective and descriptive study of newly diagnosed GCA patients who underwent PET between july 2020 and october 2021. 1990 ACR criteria (2) and/or physician criteria was used to classified patients as having GCA. Clinical and radiological features were described. All patients should not be taken any other inmunosupresant drug but glucocorticoids (GCs). Results Fourteen consecutive patients were diagnosed as GCA. Eight patients were female with a median age of 64.4 years. All patients but one underwent temporal artery biopsy (TAB) with a positive result in 54%. PET was positive in 85.7% patients. The median dose of GCs when PET was done was 31.4 (0-45) mg/day and the median delay in PET performance was 8 days (0-22). The 2 patients with negative PET had positive TAB. Proximal thoratic aorta involvement was observed in all patients with positive PET. Late PET images were taken in 6 patients with a median dose of GCs of 43,3 mg/day and median delay of 11,3 days with positive result in all of them (Table 1). Table 1. PET late images PET LATE IMAGES N=6 -SEX (female) % 66 -AGE (years) 60.1 -BAT (positive) % 40 -PET RESULT (positive) % 100 -GCs DOSE (mg) 43.3 (40-45) -DAYS OF DELAY 11.3 (3-22) Conclusion Despite the high dose of GCs and the delay in PET performance, in our serie PET has diagnosed LVV in 85,7% of GCA patients. PET within 3 days after start GCs, has been usefull to diagnosed extracranial involvement in GCA (3). In our series the prevalence of extracranial involvement diagnosed by PET in GCA has been higher than others published until now (2). Further patients are needed to confirm these data. References [1]Braun J, Baraliako sX, Fruth M. The role of 18F FDGpositronemissiontomography for the diagnosis of vasculitides. Clin Exp Rheumatol. 2018 Sep-Oct;36 Suppl 114(5):108-114. [2]Hunder GG, Bloch DA, Michel BA, Stevens MB, Arend WP, Calabrese LH et al. The American College of Rheumatology 1990 criteria for the classification of giant cell arteritis. Arthritis Rheum 1990;33(8):1122–8. [3]Slart, Riemer H J A et al. “FDG-PET/CT(A) imaging in largevessel vasculitis and polymyalgiarheumatica: joint procedural recommendationofthe EANM, SNMMI, and the PET InterestGroup (PIG), and endorsedbythe ASNC.” Europeanjournalof nuclear medicine and molecular imaging vol. 45,7 (2018): 1250-1269. Acknowledgements The authors thank the Spanish Foundation of Rheumatology, Roche and Janssen for providing funds to make this study. Disclosure of Interests Vicente Aldasoro Speakers bureau: Roche, Lilly, Novartis, MSD, Janssen, Abbvie, Paid instructor for: Roche, Lilly, Grant/research support from: Roche, Janssen, Maria José Garcia Velloso: None declared, Jose Ángel Richter Echevarria: None declared